Apps I Love: F.lux and Twilight

I’ve been struggling for over a week to get over a stupid cold – and I am finally seeing it break after (spoiler) running a marathon yesterday. Hooray! Running always seems to cure my maladies :)

While I’ve been sick, I’ve been trying extra hard to get more sleep… but it’s not always easy. I schedule myself way too thin! Lately, I am trying to take at least one night a week for myself, with nothing scheduled at all. No plans with friends, no booked gym classes, and not even plans to hit anything on my to-do list. Generally when I’ve been able to take that time, I’ve spent it reading, taking myself out to a nice dinner, or hitting the elliptical – but it’s really decreased my stress levels to have a night set aside where I don’t have to do anything.

However, one of my biggest disruptors of sleep is something that I really can’t get out of my life – all my electronic devices! I am the queen of bringing my cell phone and laptop into bed with me to finish/check “just one more thing” before I go to bed. Unfortunately, numerous studies have shown that the blue light our electronics emit can interfere heavily with our circadian rhythms – meaning that if you use your laptop/tablet/smartphone right before bed, you’ll probably have a harder time falling asleep. But I’m a tech addict! What do I do?

I discovered two apps that help me avoid this problem, while still allowing me to always stay connected. (Yes, I know I am basically just putting a band aid on the problem of being an email addict… but it’s better than doing nothing about it.) Both apps work in similar ways, adapting the color of your display screen to the time of day instead of being a monotonous blue at all times. You may only notice the blue glow when it’s dark, but your device is actually emitting that light at all times – you just don’t notice it in the daytime when you’re (presumably) in a brightly lit room or with sunlight streaming in the windows. Seeing this bright blue light at night can wreak havoc on your sleep – and that’s where changing the tint of your screen can help.

The first (and best-known) app I downloaded was F.lux, which works on Windows, Max, Linux, and iPhone/iPad. I’ve used F.lux for several years now on my laptop with no problems. At times I do notice the kind of orange-y tint to things (most notably when I was redesigning my blog and trying to choose colors for the logo at 10pm) – but it’s easy to right click the icon in your system tray to “disable for an hour” if you are doing similarly color-sensitive work.


F.lux is incredibly easy to set up and use – the screen shown above is actually the advanced options! To use it, just install, input your location, and the settings above are the default. But if you want to get really fancy, you can customize the colorization on a scale of halogen to fluorescent to daylight, and you can also adjust the transition speed. I actually love the 20 second transitions because they kind of serve as a warning to me of how late it’s getting, particularly if I’m still at the office when I notice the tint change!

The only thing I don’t like about F.lux is that I have to manually adjust my location instead of having it somehow tied to my timezone (which I have enough trouble remembering to reset when I’m flying around the country). Since I spend half my week in Dallas and half in New York City (or somewhere else on my marathon travels!), I usually don’t remember to change the settings on F.lux to wherever my location is, and I just leave it permanently set to Dallas. I figure that’s only at most an hour or two off from most of the places I visit anyway, so it still does a decent job. I realize that setting it to a timezone rather than a location would be less accurate, but since I don’t bother to change it at all, it would be more accurate than the alternative! That said, I also know that my weekly travels make me an edge case among users :)

While I installed F.lux a few years ago, it never quite occurred to me that perhaps I ought to look for a similar app for my phone. When it first came out, F.lux was Windows-only; now, it’s also available for Mac, Linus, and iPhone/iPad. But I’m an Android girl! Luckily, in the last week, I found an alternative that works great on my phone: Twilight. (Thank you to the Lifehacker podcast for the rec.)

Twilight is a completely free app that is on the Google Play store, but it has a few more advanced features than my good ol’ F.lux. I honestly found it a little bit overwhelming at first! Here are the presets I settled on:


Because Twilight accesses the GPS on your phone, there’s no need to ever update your location – the app does it for you. Hooray! And then if you don’t mind spending a few bucks ($2.49), you can unlock “pro” settings that allow you to use custom times and adjust the transition time to anything you want (default is 90 minutes, so a bit slower than F.lux). I haven’t yet sprung for the pro settings since I just got the app a week ago and was still test driving it, but I’m already pretty in love with it. It’s so nice to be able to wake up in the middle of the night, check my email, and not have a bright blue screen glaring back at me and waking me up! (Again, I know that I am crazy for doing things like checking my email in the middle of the night when I wake up… but let’s just ignore that for now.) I’d like the ability to set it to specific bedtimes (e.g., bright starting at 6am and not getting dark until 9:30pm, regardless of sunrise/sunset), and for less than the price of a cup of a coffee to wake me up in the morning, I think it’s definitely worth it.

Thoughts? Other similar/better apps I should check out? Please note that neither F.lux nor Twilight had anything to do with this review in either soliciting it or paying me for it; they are just both apps that I love and wanted to share!


  1. ankit singh says:

    I am from India. I am using Twilight and very much impress by its performance.
    I was in search for similar app for my laptop and now I found one. Thank you

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